\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\title{Exercise 7:Math Formula}
\begin{document}
\maketitle
\section{Math Simple Formula}
    Add $a$ squared and $b$ squared to get $c$ squared. 
    Or, using a more mathematical approach: \mbox{$a^2 + b^2 = c^2$}
     \vspace{1cm}
     
    \begin{multline} 
    \label{math:formula1}
    a + b + c + d + e + f + g + h + i = j + k + l + m + n       
    \end{multline}
    
    \begin{align}  
        a & = b + c
        & = d + e + f + g + h + i
        + j + k + l
        & + m + n + o
        & = p + q + r + s
    \end{align}
    In Formula~\ref{math:formula1}, it shows ....
    \vspace{1cm}
\section{Math Fonts and Symbols}

    Let \( \mathcal{T} \) be a topological space, a basis is defined as
     \[
    \mathcal{B} = \{B_{\alpha} \in \mathcal{T}\, |\,  U = \bigcup B_{\alpha} \forall U \in \mathcal{T} \}
     \]
    
    \vspace{1cm}
   

    \begin{align*}
    RQSZ \\
    \mathcal{RQSZ} \\
    \mathfrak{RQSZ} \\
    \mathbb{RQSZ}
    \end{align*}
    
    \begin{align*}
    3x^2 \in R \subset Q \\
    \mathnormal{3x^2 \in R \subset Q} \\
    \mathrm{3x^2 \in R \subset Q} \\
    \mathit{3x^2 \in R \subset Q} \\
    \mathbf{3x^2 \in R \subset Q} \\
    \mathsf{3x^2 \in R \subset Q} \\
    \mathtt{3x^2 \in R \subset Q} 
    \end{align*}

\end{document}